Jv. Ward et al., Influence of ground water on surface water conditions in a glacial flood plain of the Swiss Alps, HYDROL PROC, 13(3), 1999, pp. 277-293
Hydrological exchange processes in alluvial flood plains occur along severa
l major pathways operating at different scales. Ground water-surface water
interactions exert major control on structural and functional attributes of
stream ecosystems. The role of ground water on environmental conditions in
surface water habitats was investigated as part of a holistic ecological s
tudy of Val Roseg, a complex glacial flood plain in the Swiss Alps. Six cha
nnel types were identified based on surface hydrological connectivity with
the main channel and water source: the main channel, side channels, intermi
ttently-connected channels, mixed channels, groundwater channels, and tribu
taries. The groundwater channels have no upstream connection with surface c
hannels since they are fed by alluvial or tributary aquifers. Compared with
Other channel types, groundwater channels are characterised by relatively
high and constant temperatures, low turbidity, and high specific conductanc
e, bicarbonate and nitrate concentrations. Different types of groundwater h
abitats were delineated, based on their silica concentrations and temporal
patterns of specific conductance. Increases in the concentrations of major
ions with declining discharge clearly show a shift from a glacier meltwater
-dominated flood plain in summer to a groundwater-dominated system in autum
n and winter. A conceptual model was developed to portray the different gro
undwater reservoirs and flux pathways thought to structure the habitat temp
late of the Val Roseg hydrosystem. This model serves as a framework for fut
ure studies of the role of ground water in sustaining what appear to be div
erse and abundant benthic and interstitial communities in this harsh enviro
nment. Copyright (C) 1999 John Wiley & Sons, Ltd.